The present invention generally relates to methods and machines for cutting products, including but not limited to food products. The invention particularly relates to machines equipped with a cutting head and an impeller assembly adapted to rotate within the cutting head, wherein the impeller assembly transports products to knives situated in the cutting head for slicing the products into slices or chips of the lattice type.
Various types of equipment are known for slicing, shredding and granulating food products, as nonlimiting examples, vegetables, fruits, dairy products, and meat products. Widely used machines for this purpose are commercially available from Urschel Laboratories, Inc., and include machines under the names Model CC® and Model CCL. The Model CC® and CCL machines are centrifugal-type slicers capable of slicing a wide variety of products at high production capacities. Whereas the Model CC® line of machines is particularly adapted to produce uniform slices, strip cuts, shreds and granulations, the Model CCL line is particularly adapted to produce slices or chips of a waffle or lattice type (hereinafter, collectively referred to as a lattice), nonlimiting examples of which are represented in FIG. 1.
From top to bottom, the images in FIG. 1 represent fine, coarse, and deep lattice cuts, which may be used to produce, as nonlimiting examples, lattice potato chips and potato waffle fries. As evident from FIG. 1, the opposing surfaces of the slices are characterized by a periodic pattern having a corrugated or sinusoidal shape with rounded peaks and valleys when viewed edgewise, though sharper peaks and valleys are also possible. The lattice cut is produced by sequentially crosscutting a product at two different angles, typically ninety degrees apart, using one or more knives each having a cutting edge formed to have the desired periodic pattern of the slices to be produced. Such a knife is referred to herein as a corrugated knife, which is intended to denote the presence of a cutting edge on the knife that is characterized by peaks and valleys when the knife is viewed edgewise, but is not restricted to cutting edges having peaks and valleys with any particular shape or pattern, periodic or otherwise.
Original versions of the Model CCL are represented in U.S. Pat. Nos. 3,139,127 and 3,139,130, whose contents are incorporated herein by reference. A representation of a Model CCL machine 10 is shown in FIG. 2, and drawings of a Model CCL machine 10 adapted from U.S. Pat. Nos. 3,139,127 and 3,139,130 are included herein as FIGS. 3 through 5. The machines 10 depicted in FIGS. 2-5 include a frame 12 that supports a power unit 14, a stationary cutter assembly (cutting head) 16, and a carriage or conveyor (impeller) assembly 18 that is rotatably disposed within the cutting head 16 for feeding products to the cutting head 16. The cutting head 16 and impeller assembly 18 are coaxial, and the cutting head 16 remains stationary while the impeller assembly 18 rotates within the cutting head 16 about their common axis. The cutting head 16 and impeller assembly 18 are enclosed in a housing 20, and products are delivered to the cutting head 16 and impeller assembly 18 through a feed hopper 22. FIG. 4 represents a perspective view of the machine 10 of FIG. 3, with the hopper 22 retracted and the housing 20 and cutting head 16 removed to expose the impeller assembly 18, which is represented as having four tubular guides 24 that deliver products to the cutting head 16. FIG. 5 is an isolated top fragmentary view of the cutting head 16 and impeller assembly 18, and shows corrugated cutting knives 26 mounted at the perimeter of the cutting head 16, each secured to a segment 28 of the cutting head 16 between a knife holder 30 and clamp 32. The assemblage of a knife 26, knife holder 30, and clamp 32 forms what will be referred to herein as a knife assembly 34. From FIG. 3, it is evident that the interior of the cutting head 16 has a spheroidal surface. Consequently, the knives 26, knife holders 30, and clamps 32 also have spheroidal shapes.
The hopper 22 delivers products to the impeller assembly 18, and centrifugal forces cause products to move outward into engagement with the interior spheroidal surface of the cutting head 16, including the interior surfaces of the knife holders 30. The interior surfaces of the knife holders 30 are referred to herein as registration surfaces of the knife holders 30. While engaged with the registration surfaces, in regular succession the products encounter and are sliced by the knives 26 circumferentially spaced within the cutting head 16.
FIG. 6 represents a fragmentary perspective view of a cutting head 16 and impeller assembly 18 corresponding to the machine 10 shown in FIG. 5. FIG. 6 is useful for further describing operating principles of the Model CCL. Product delivered to the feed hopper (not shown) enters the impeller assembly 18 at {circle around (1)}. The impeller assembly 18, including its four rotating tubular guides 24, rotates about the vertical axis shared with the cutting head 16. Centrifugal forces urge products 35 within the tubular guides 24 radially outward through the tubular guides 24 toward the radially outward extremities {circle around (2)} thereof. The tubular guides 24 are driven to rotate about their respective axes so that the product 35 within each guide 24 is rotated about its horizontal axis while the impeller assembly 18 rotates about its vertical axis. As centrifugal forces hold the products 35 tightly against the spheroidal interior surface of the cutting head 16, the tubular guides 24 cause the products 35 to make an approximate one-quarter turn between each of four knife stations {circle around (3)}, resulting in the desired lattice cut being generated in slices 36 as the knives 26 are encountered.
FIG. 7 is an isolated perspective view of a cutting head 16 of a CCL machine 10 corresponding to the machine 10 shown in FIGS. 5 and 6. The cutting head 16 is again shown as comprising segments 28 that define the spheroidal interior surface of the cutting head 16, and corrugated cutting knives 26 secured to each segment 28 between a knife holder 30 and clamp 32. FIG. 8 evidences the curvature of a knife 26, knife holder 30, and clamp 32. As evident from FIGS. 7 and 8, the knife holder 30 defines a knife seat 44 that has a smooth cylindrical surface on which a knife 26 of essentially any shape can be placed. Likewise, the knife clamp 32 has a simple arc on its leading (clamping) edge to clamp the knife 26 against the knife holder 30. The clamp 32 visible in FIG. 7 can be seen to have a tapered outer surface 32a at its leading edge (generally conical as a result of the arcuate shape of the clamp 32) to gently direct slices up and over the clamp 32 as they leave the cutting head 16. As evident from FIG. 8, the peaks and valleys of the knife 26 and simple arcuate shapes of the knife holder 30 and clamp 32 result in the presence of gaps or openings 38 between the knife 26 and both the knife holder 30 and clamp 32.
Further descriptions pertaining to the construction and operation of Model CCL machines are contained in U.S. Pat. Nos. 3,139,127 and 3,139,130.
CCL machines of the types described above have performed exceedingly well. Even so, as is apparent from FIG. 8, as products and slices pass over the knife holder 30 and clamp 32, a portion of the product and slice may scrape the leading edges of the holder 30 and clamp 32. Over time, the openings 38 between the shaped knife 26, knife holder 30 and clamp 32 may accumulate solids, for example, starch if the product being sliced is a vegetable or fruit. Though such accumulation does not pose an issue with well-maintained machines, if unattended the accumulated solids may eventually lever the knife 26 off the knife seat 44 of the knife holder 30, resulting in the production of thinner slices. If, as a result, the knife 26 is no longer rigidly registered against the knife seat 44 of the knife holder 30, the leading (sharp) edge of the knife 26 can become destabilized, diminishing slice accuracy and quality. Another issue that may be encountered is that, due to the dual rotary nature of the slicing action on a CCL machine, i.e., products rotating about the horizontal axis of the tubular guides 24 while also rotating about the vertical axis of the impeller assembly 18, the knives 26 may experience a force that is transverse to the slicing force that occurs in a roughly horizontal direction. Over time, this transverse force may result in vertical movement of the knives 26 (i.e., parallel with the axis of rotation of the impeller assembly 18), indicated by the arrow 40 in FIG. 8. These circumstances may become exacerbated by increasing the amplitude of the peaks and valleys of the knives 26, for example, the coarse and deep lattice cuts in comparison to the fine lattice cut depicted in FIG. 1.